Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange
Join us in building a kind, collaborative learning community via our updated Code of Conduct.

Questions related to the physical processes involved in or to the observations of the process of forming a star.

5
votes
2answers
129 views

The formation of new stars as depicted in Feynman's lectures

I've stumbled upon this curious passage addressing the formation of stars in Feynman's lectures on physics: Whether we have ever seen a star form or not is still debatable. Figure 7–12 shows the ...
5
votes
2answers
70 views

What does the ']' in the spectral line “CIII] 1909 Å” mean?

The above emission line, as I understand, is a useful probe of early star-forming galaxies. However, I do not understand what the ']' to the right of the 'CIII' means. I could not find any online ...
-6
votes
1answer
65 views

Black-hole becoming a star again - follow-up question [closed]

Some questions have been posed about black holes becoming stars again once they attract enough hydrogen/atomic matter from another star. Some answers were a forceful NO. Never. However - let's ponder ...
2
votes
0answers
33 views

What's the profound reason(s) why the star formation rate drives the scatter of the mass-metallicity relation in galaxies?

Since decades it's well known that a correlation between stellar mass and metallicity (Z; both stellar and gas-phase Z, but here I focus on the gas-phase Z) exists (e.g., Tremonti+04; analysis of >...
5
votes
1answer
280 views

Black Dwarf Capabilities

Can a black dwarf be suitable for manned exploration, once it cools down? And potentially used for space mining?
10
votes
2answers
125 views

Star formation around rotating black holes?

Please excuse an amateur question. While trying to think of anything but what was happening during a dental procedure my mind turned to a model of a star close to a rotating black hole and the ...
1
vote
0answers
34 views

Doubt about star formation [duplicate]

When a star runs out of hydrogen, it either goes through supernova or forms white dwarf and planetary nebula. So there should not be much hydrogen left to form a new star in the nebula. So how new ...
0
votes
0answers
44 views

What heats up the stars? [duplicate]

So recently, I was reading about nuclear fusion. It's really very hard to start nuclear fusion, artificially, because it needs very high temperature (Somewhere around 100 million degrees). These type ...
27
votes
1answer
5k views

If two white dwarfs collided, would they become a star?

Would the temperatures during such a collision be able to ignite nuclear fusion, bringing the dead star back to life? If so, would it only be able to fuse for a short time before running out of fuel, ...
2
votes
2answers
135 views

Will all of the gas in the universe be converted into red dwarf stars?

Red dwarfs have lifespans of trillions of years and are also the most abundant stars, making up 70% of the stars in the Milky Way. No red dwarf star has ever died and none will die for a very, very ...
11
votes
2answers
706 views

How did the lighter elements end up in the center of the solar system? Solar System Formation

The previous generation of stars famously are the origin of all the heavier elements (up until iron?) in the solar system. So a big portion of the solar system mass actually is made up of Carbon, ...
4
votes
2answers
129 views

If two binary brown dwarfs began to exchange gas with each other, would they both ignite into stars?

If two brown dwarfs got close enough to exchange gas with each other, could it trigger nuclear fusion within their cores? Is it possible for two brown dwarfs to orbit so closely and become a ...
2
votes
3answers
163 views

Term for the moment when hydrogen fusion begins in a star

I have read of this process many times, but I don't think I know the term specifically for the moment when hydrogen fusion begins. What is this moment called?
3
votes
1answer
195 views

How was the Sun formed?

Refer to the below minutephysics video, in which they say that in order to reach the Sun from earth, we must first stop revolving around the Sun ie make our tangential velocity zero, and then head ...
4
votes
1answer
104 views

What are infall signatures in stars?

I came across several papers (e.g. Looking for outflow and infall signatures in high mass star forming regions P. D. Klaassen, L. Testi and H. Beuther, 2011) talking about infall signatures in star ...
2
votes
3answers
188 views

How do we calculate heat flow or cooling rate for no fusion brown dwarf star?

I was reading this article and it said something that didn't sit right with me. "SIMP0136 still gives off light mostly in the infrared wavelengths, as its temperature is now approximately 830° C (1,...
0
votes
1answer
59 views

Spacing of G and K class stars

I was looking at the Wikipedia article "List of potentially habitable exoplanets" and I noticed that many of the closest planets listed(tens or hundreds instead of thousands of light-years away) ...
4
votes
1answer
138 views

What are IRAS sources?

Do IRAS sources refer to star forming regions? I searched google and I came to know that it stands for IR astronomical satellite.But what do they search for? Please help me
6
votes
1answer
94 views

How long will star formation endure before the eventual heat death of the observable universe?

Lord Kelvin's prediction of heat death indicates the eventual end to star formation in the observable universe. Have any astrophysicists made any predictions for the endurance of star formation in the ...
13
votes
2answers
940 views

How are binary star systems created?

I don't know how common it is for a system to have two stars (or perhaps even more) but how do they arise? Is that due to the stellar accretion disc, or the composition of the stellar nebula? Or are ...
7
votes
2answers
355 views

How were the first stars formed?

In class, we read a Scientific American article, "Cloudy with a Chance of Stars" that explained how the cores and the dust around them formed stars(he called them eggs for a chicken/egg analogy, where ...
1
vote
0answers
44 views

Looking for Galactic Data

I am doing some personal research and just and am trying to find a decent source for galactic data. Specifically I am looking for a database that includes the estimated size of the galaxy's ...
4
votes
1answer
115 views

Sky in the very far future / past

Motivated by this question about a stranded submarine in the Jurassic I would like to know: Is there anything remotely left of our current skyline if we go back or forward millions of years so that ...
3
votes
0answers
184 views

What characteristics or patterns do galaxies have on color-luminosity chart? [closed]

For the following graph, I have some confusions: How do galaxies rank by mass? We know that on main-sequence, more luminous stars are also more massive, so I guess it also applies to galaxies. Do red ...
0
votes
1answer
277 views

How do we know a star's age based on its spectrum? [duplicate]

A star's nearby environment may give clue to its age. Different stellar type have different spectral features. If we just have its spectrum, how do we know its age? For example, a star may be born ...
0
votes
1answer
106 views

I have some questions about star formation [closed]

Q2 What does the phrase 'containing several distinct knots of collopsing material' mean? Q3 In this context, does the word 'such clouds' mean protostar? (I'm not an English-native speaker.) Q4 In ...
4
votes
2answers
227 views

Sun's formation as “part of a star-forming-cluster…”?

After reading this interesting answer, I was wondering, do we in fact know if our Sun in particular was created as part of a star-forming-cluster, or, was it more of a solo creation? (Or, are all ...
5
votes
1answer
177 views

What is the origin of the dust near the sun?

In this question I asked about the Solar Probe Plus mission. Reading a 2008 report I saw that there is an elevated exposure to high velocity dust near the sun. I understand the high velocity, anything ...
5
votes
3answers
1k views

Could the earth become a star if more mass was added?

I've heard that the only difference between a star and a planet is mass, meaning that if planets accredited enough mass they would too become stars. Does this mean that the star started off as a ...
3
votes
1answer
134 views

Star formation: When a nebula collapses, is it only the gasses that form the star?

A nebula is made of dust (elements heavier than He and H) and gas (H and He). Stars are made when nebulae's collapse and hydrogen begins to fuse. 99% of nebula material goes into making the star. The ...
1
vote
1answer
263 views

How to show that the Jeans Criterion for Mass, Radius and Density are equivalent?

The gravitational collapse of a gas cloud can be described by the Jeans Criterion for mass, radius and density of the gas cloud, which is (c stands for cloud): $$M_J = (\frac{5kT}{G \mu m_H})^{3/2} (...
1
vote
1answer
87 views

Luminosity L(t) for a homologously contracting star

I'm dealing with a homologously contracting star with Mass M, Radius R and a gravitational binding energy of $E = -a GM^2 / R $ (a is a constant). I was looking for a way to find an expression ...
1
vote
2answers
128 views

How can we explain high redshift numbers?

I just finished an introductory astrophysics course$^1$ and I have a lingering question that I can't seem to resolve. We learned that for the first few hundred million years, the universe was pretty ...
4
votes
1answer
173 views

Why dust is optically thin in Far Infrared wavelengths?

What is the actual meaning of the statement 'Dust is optically thin in the Far Infrared (FIR) over most of the Galaxy'? Kindly Help
2
votes
1answer
190 views

What does “EW(Hα)” mean?

I came across a website saying that classical T Tauris have an "EW(Hα) > 5 angstroms". Does anybody know what "EW" means? Thanks.
2
votes
1answer
89 views

How can ionized emission line flux decrease as a function of increasing metallicity or abundance?

The chemical evolution of galaxies is an important way to learn about their formation and stellar/gaseous constituents. Many galaxies show narrow emission lines at optical wavelengths (3500-9000 ...
2
votes
1answer
62 views

If a star were to suddenly lose nearly all of its stored heat, would it be able to return to its normal state? [closed]

If not, would it be possible to approximate the maximum heat energy a star could lose before the change became irreversible?
5
votes
1answer
209 views

Are there any hot jupiters orbiting red dwarfs?

Do we know of any hot jupiters that could be orbiting a red dwarf (or, more probably, orbiting a barycenter between the two)? Is this scenario even physically possible?
1
vote
1answer
87 views

Could dark matter assist with star formation?

This is related to the question: "Can dark matter decrease the Jeans length?" If dark matter assists in any way with star formation, shouldn't it be detectable by precisely measuring velocities in ...
4
votes
1answer
944 views

Where do new stars get their hydrogen from? [duplicate]

When stars run out of hydrogen, they explode (though they also use heavier elements for some time) and form nebulae. In the nebulae, new stars are born which use hydrogen as their fuel. So, my ...
4
votes
1answer
183 views

Why do pre-main sequence stars show lithium in absorption?

This paper and this paper state without discussion that the presence of lithium absorption in the stars they observe as strong evidence of these stars being pre-main sequence stars. Because they state ...
1
vote
0answers
26 views

Star Formation in the future [duplicate]

From what I understand stars form in dense clouds of hydrogen and helium molecules. Only so much hydrogen and helium were "created" from the Big Bang or rather formed if you may. Is it conceivably ...
1
vote
1answer
72 views

Could a “burping” supermassive black hole be responsible for a spiral galaxy's look?

I read an article which suggests black holes could influence the production of stars in the galaxy as the black hole can burst out powerful X-rays to "snowplow" the surrounding dust and gas. Although ...
3
votes
5answers
661 views

Fusion of elements inside heavy stars

I am confused with nucleosynthesis inside supernovae. I have read that the heavier elements are made through fusion of lighter element's namely hydrogen and helium. Does the star "store" all the ...
5
votes
2answers
133 views

Can dark matter decrease the Jeans length?

I am wondering if there are any models of interstellar cloud collapse out there which take dark matter into account. If dark matter has local perturbations or density fluctuations, then that may be ...
3
votes
5answers
1k views

Why does gravity increase in star formation?

When a star ignites ( ie. fusion starts ), the star maintains its form by balancing gravity's inward pressure, and radiation's outward pressure. I get that the fusion of hydrogen atoms releases ...
4
votes
1answer
297 views

How is the Lithium Depletion Boundary used to determine the age of a stellar cluster?

According to my understanding of Soderblom et al. (2014), lithium ages of stars are determined as follows: Determine lithium abundance from equivalent width measurement of Li$_{\mathrm{I}}$ ...
3
votes
1answer
940 views

What is the largest hydrogen-burning star?

I am wondering what is the largest known core hydrogen-burning star? A look at the list of largest known stars on Wikipedia seems to indicate VV Cephei B (at the bottom of the list), but I would like ...
1
vote
1answer
250 views

What is the mass limit in a stellar accretion disc?

I became curious about the maximum mass in a star's accretion disc while watching an episode of Star Trek involving a Dyson Sphere. I wondered if some maximum amount of stellar material would limit ...
4
votes
3answers
342 views

Are there heavenly bodies between galaxies?

I do understand that galaxies were formed in the famous Big Bang. However, I also understand that if such an explosion occurs in empty space it will never form distinct galaxies, it should more or ...